1. Field of the invention
The present invention concerns overmolding joint boxes and repeater housings during the laying or repair of underwater cables. It applies in particular to a machine for overmolding such equipments of an underwater cable, the method of using it and equipments overmolded using the machine.
2. Description of the prior art
An underwater cable comprises the line cables, repeaters in housings equipped with access cables (tail cables) and joint boxes in which two line cables are connected together or a line cable is connected to a repeater access cable. Each joint box and each repeater housing is cylindrical with a conical portion at each end. The joint boxes and repeater housings are covered with a polyethylene jacket sealing and electrically insulating the cable from the surrounding seawater and continuous with the jacket of the line and access cables.
The jacket is overmolded onto the boxes and housings. The techniques used until now carry out the overmolding operation separately by first overmolding the central cylindrical part and subsequently overmolding the conical end parts, achieving continuity on either side of these end portions with the jacket of the line or access cable concerned and with the central overmolding applied previously. For each of these operations the overmolding is performed by injecting the required volume of polyethylene slowly and at a low pressure into the cavity of a mold.
These overmolding operations take a long time. They give rise to four interface areas between the central overmolding, the two end overmoldings and the polyethylene jackets of the line and/or access cables concerned. The protection can be improved at these interface areas by means of heat-shrink sleeves threaded over the cables and the central overmolding and slid into place after the end overmoldings are done.
An object of the present invention is to reduce significantly the overall duration of overmolding each equipment of an underwater cable, to reduce thereby the cost of overmolding carried out in the factory or on the cable laying ship, and to reduce the number of interface areas produced and consequently the risks of defects in these interface areas.